Transmitting and distributing audio current on an amplified loudspeaker system



Aug. 8, 1939.

G. M MARR TRANSMITTING AND DISTRIBUTING AUDIO CURRENT ON AN AMPLIFIED LOUDSPEAKER SYSTEM Filed Oct. 9, 1937 INVENTOR Jung/ 7H. OHM

Patented Aug. 8, 1939 TRANSMITTING AND DISTRIBUTING AUDIO CURRENT ON AN AMPLIFIED LOUDSPEAK- ER SYSTEM George Marr, Woodhaven, N. Y.

Application October 9, 1937, Serial No. 168,159

5 Claims.

This invention relates in general to loud speaker circuits and more particularly to an amplified loud speaker system adapted for the transmission and distribution of radio currents.

An object of the invention is to provide an improved method for connecting various groups of loud speakers to a main amplifier by means of a wiring circuit that will insure a positive source of current supply at all times. This I accomplish by the use of a double Or looped circuit, so that in the event of any one feeder circuit being rendered inoperative, the duplicate or looped circuit will be instantly brought into effect.

With reference to a conventional and familiar loud speaker system known as a public address system which consists ordinarily of a source of power, an amplifier and a control panel, a microphone and a plurality of loud speakers, it might be said that in such a system one or more loud speakers may be connected directly to the impedence or repeat coils located within the amplifier cabinet. Practice has shown that no more than two loud speakers may be operated successfully from one impedence coil and where considerable numbers of loud speakers are to be used in one auditorium, it is necessary to install a number of feeder circuits from the amplifier to the loud speakers. While such an arrangement might not be objectionable in a building, it would however have its objections when installed aboard ship.

This system, the subject of this invention, was designed with the special requirement of shipboard installation in mind. While its object is primarily to provide a reliable transmission clrcuit, its further object is to reduce the number of conductors to be installed external of the amplifier cabinet and connecting the loud speakers to the amplifier. Also, to provide alarm signals for each branch feeder circuit to indicate either an open or a short circuit on either wire of any circuit and to provide an automatic means for transferring feeder current from the wires affected to the wires of the duplicate circuit remaining clear of grounds or shorts.

Various: objects and advantages of the invention will be in part obvious from a careful inspection of the accompanying drawing and claims hereinafter provided.

Variations may be resorted to within the scope of the invention and portions of the improvements may be used without the others, whilst not departing from the spirit of the invention.

In the drawing:

Figure 1 is a diagrammatic illustration of the invention. Figure 2 is a diagrammatic illustration of the interior of an auxiliary amplifier cabinet. Figure 3 illustrates the interior of a main amplifier cabinet.

With reference to Fig. 1 of the drawing, [0 5 designates a control panel comprising a microphone It and switches l2. A multiple conductor cable l3 connects the control panel to the main amplifier cabinet l4. Twin conductor circuits i6 and II connect the main amplifier cabinet [4 to 10 the auxiliary cabinet I8, the circuit It being an exact duplicate of the circuit I I whilst disposed as far remote therefrom as possible so that the same will not be subjected to the same local conditions that might endanger the operation of the 16 other circuit and the system as a whole.

Loud speakers are designated by 99 said speakers being connected to the impedance coils 2G by the connectors 2i.

With reference to Fig. 2 which illustrates the 20 interior of an auxiliary amplifier cabinet, there is shown the various impedance coils 29, one for each loud speaker, and the manner in which they are connected to each other and to the main feeder transformer 22 of which there is one pair provided for each circuit. These transformers are connected to the output transformer 25 (Fig. 3), located in the main amplifier cabinet, by the twin conductors It and I1 hereinbefore described.

In practice and especially when installed aboard ship, the twin circuits It and I! will run along separated paths-for instance: one circuit will run for and aft on the starboard side of the ship and the other on the port side of the ship.

With reference to Fig. 3, a balanced relay 26, adapted to indicate open or short circuits has connection with the secondary of the transformer 25 and communicates with suitable trouble lights (not shown) through the medium of the circuits 29, 3|]. Dual feeder circuits l6, ll connect with 40 a double throw switch manually or automatically operated at 28, said switch being in turn connected to a balanced relay 26.

Variations may be resorted to within the scope of the invention and portions of the improve- 45 ments may be used without the others whilst not departing from the spirit of the invention.

Having thus described my invention I claim:

1. In an electrical signaling device, the combination of, a main feeder circuit, a dual feeder circuit disposed remote from the first said circuit; both of said circuits being normally on and either one being adapted to effectively transmit the full energy required for the operation of the signaling device as connected to both of said circuits.

2. In an electrical circuit for energizing an instrument or appliance, the combination of, a main feeder circuit, a dual feeder circuit disposed remote from the first said circuit and connected to the same terminals; only one of said circuits being normally on, and current transfer means adapted to change over from one circuit to the other the current transmitted.

3. In apparatus of the class described, in combination, a plurality of loud speakers, multiple output transformers, dual feeder circuits leading from said loud speakers to said transformers; either of said circuits being adapted to transmit adequate energy for all of said loud speakers.

4. In apparatus of the class described, in combination, at least one electrically actuated signal means, at least one output transformer, dual feeder circuits leading from said transformer to said signal means; one of said circuits being normally inactive, means for indicating an open or short circuit on the normally active circuit, and means to transfer electrical energy from one to the other of said circuits.

5. In a signaling apparatus, the combination of, a plurality of electrically actuated signal means, multiple output transformers, multiple power transformers, dual feeder circuits widely spaced apart connecting said output transformers to said power transformers; either one of said circuits being adequate to carry full electrical energy 15 to and from said transformers.

GEORGE M. MARE. 

